[Tarantool-patches] [PATCH luajit] Fix jit.dump() output for IR_CONV.

[Sergey Bronnikov]

Hi, Sergey!
Thanks for the patch!
LGTM

On 10/25/23 16:14, Sergey Kaplun wrote:
> From: Mike Pall <mike>
>
> (cherry-picked from commit 44bd7437a27e0d19bcf878c20ad27a673f17f40b)
>
> When dumping IRs via `jit.dump()`, the incorrect value of `IR_CONV` mode
> shift (`IRCONV_CSH`) is used. This patch fixes the value.
>
> Sergey Kaplun:
> * added the description and the test for the problem
>
> Part of tarantool/tarantool#9145
> ---
>
> Branch: https://github.com/tarantool/luajit/tree/skaplun/fix-ir-conv
> Tarantool PR: https://github.com/tarantool/tarantool/pull/9307
> Issue: https://github.com/tarantool/tarantool/issues/9145
>
>   src/jit/dump.lua                              |  2 +-
>   .../fix-jit-dump-ir-conv.test.lua             | 68 +++++++++++++++++++
>   2 files changed, 69 insertions(+), 1 deletion(-)
>   create mode 100644 test/tarantool-tests/fix-jit-dump-ir-conv.test.lua
>
> diff --git a/src/jit/dump.lua b/src/jit/dump.lua
> index 27b5c2ae..84fe0044 100644
> --- a/src/jit/dump.lua
> +++ b/src/jit/dump.lua
> @@ -277,7 +277,7 @@ local litname = {
>       local s = irtype[band(mode, 31)]
>       s = irtype[band(shr(mode, 5), 31)].."."..s
>       if band(mode, 0x800) ~= 0 then s = s.." sext" end
> -    local c = shr(mode, 14)
> +    local c = shr(mode, 12)
>       if c == 2 then s = s.." index" elseif c == 3 then s = s.." check" end
>       t[mode] = s
>       return s
> diff --git a/test/tarantool-tests/fix-jit-dump-ir-conv.test.lua b/test/tarantool-tests/fix-jit-dump-ir-conv.test.lua
> new file mode 100644
> index 00000000..ed03210a
> --- /dev/null
> +++ b/test/tarantool-tests/fix-jit-dump-ir-conv.test.lua
> @@ -0,0 +1,68 @@
> +local tap = require('tap')
> +local test = tap.test('fix-jit-dump-ir-conv'):skipcond({
> +  ['Test requires JIT enabled'] = not jit.status(),
> +  ['Disabled on *BSD due to #4819'] = jit.os == 'BSD',
> +})
> +
> +test:plan(2)
> +
> +-- Test file to demonstrate LuaJIT incorrect `jit.dump()` output
> +-- for `IR_CONV`.
> +
> +local jparse = require('utils').jit.parse
> +
> +-- XXX: Avoid any traces compilation due to hotcount collisions
> +-- for predictable results.
> +jit.off()
> +jit.flush()
> +
> +jit.opt.start('hotloop=1')
> +
> +jit.on()
> +jparse.start('i')
> +
> +-- luacheck: ignore
> +local tab = {}
> +local idx = 1
> +for _ = 1, 4 do
> +  -- `int IR_CONV int.num index`.
> +  tab[idx] = idx
> +end
> +
> +local traces = jparse.finish()
> +
> +-- Skip tests for DUALNUM mode since it has no conversions (for
> +-- the same cases).
> +local IS_DUALNUM = not traces[1]:has_ir('num SLOAD')
> +
> +test:ok(IS_DUALNUM or traces[1]:has_ir('CONV.*int.num index'),
> +        'correct dump for index')
> +
> +local function trace(step)
> +  -- `int IR_CONV int.num check` for `step` conversion.
> +  for _ = 1, 4, step do
> +  end
> +end
> +
> +-- XXX: Reset hotcounters and traces.
> +jit.flush()
> +jit.opt.start('hotloop=1')
> +
> +jparse.start('i')
> +-- Compile the inner trace first.
> +trace(1)
> +-- Compile the big trace with the first trace inlined.
> +-- Needs narrowing optimization enabled.
> +-- XXX: Reset hotcounters and call the function 3 times to
> +-- compile. Needed to avoid hotcount collisions.
> +jit.opt.start('hotloop=1')
> +trace(1)
> +trace(1)
> +trace(1)
> +
> +traces = jparse.finish()
> +
> +test:ok(IS_DUALNUM or traces[2]:has_ir('CONV.*int.num check'),
> +        'correct dump for check')
> +
> +test:done(true)